Simultaneous spectrographic triangulation of an SAR arc and a hydrogen arc

An SAR arc at about L=2.8 and a hydrogen (H) arc between L=3.4 and L=4.0 were monitored from Richland and Banff throughout the night of March 23–24, 1969. The SAR arc remained stationary and during the night the 6300-A emission decreased steadily in intensity from about 1 kR to less than 300 rayleighs. In contrast, the H arc, in which Balmer-α emission reached an intensity of 1.7 kR, fluctuated by an order of magnitude in intensity, moved about vigorously, and split into two arcs in the morning. Spectrograms in the magnetic meridian display the monochromatic SAR-arc emission. The measurements show the SAR arc and H arc to be clearly separated by about 5° of latitude and apparently quite uncorrelated in behavior.